Abstract: Objective To observe the effect of ammonia concentrations and the preventing and treating effects on hepatic encephalopathy (HE) in rats by different concentrations of sodium butyrate. Methods The hepatic encephalopathy rat models were induced by intraperitoneal injection thioacetamide (TAA) after fed two weeks made mould for two days. General condition and the nerve reflection, the level of TBil, DBil, ALT, AST, NH3 in serum, the intestinal pH values and liver histopathology were detected. Results TBil, DBil, ALT, AST of each sodium butyrate groups were decreased. The intestinal pH value of sodium butyrate group A compared with model group was statistically significant (P ＜ 0.05), blood ammonia concentrations of sodium butyrate group A and group B were significantly lower than that in model group (P ＜ 0.001). In addition, sodium butyrate treatment can improve neuro-reflex, decrease the staging of HE. Conclusions The results indicated that the ammonia concentrations can be reduced because of the souring of the intestinal tract by sodium butyrate, which could also improve the psychiatric symptoms of the hepatic encephalopathy.